Technical Field
This invention relates to automatic transmissions, and specifically, to automatic transmissions of a twin clutch type including clutches provided in a systematic fashion for two systems being a speed-changing system involving shift positions for odd-numbered speeds (referred herein to sometimes simply as odd-speed shift positions) and another speed-changing system involving shift positions for even-numbered speeds (referred herein to sometimes simply as even-speed shift positions).
Background Art
As an automatic transmission to be mounted on vehicles such as automobiles in the past, there has been an automatic transmission of a twin clutch type disclosed in Japanese Patent Application Publication No. 2008-291892, including clutches provided in a systematic fashion for two systems being a speed change system for odd-speed shift positions and a speed change system for even-speed shift positions.
This twin clutch type automatic transmission included an input shaft for drive power to be transferred thereto from an engine through a torque converter, a first drive shaft disposed around the input shaft, to be coaxial with the input shaft, and adapted for use of a first clutch for a selective coupling with the input shaft, and a combination of an array of even-speed shift position drive gears and a reverse drive gear provided on the first drive shaft.
Further, this automatic transmission included a second drive shaft disposed in parallel to the input shaft and adapted for use of a second clutch for a selective coupling with the input shaft through a measure for power transfer, an array of odd-speed shift position drive gears provided on the second drive shaft, and an output shaft disposed in parallel to the input shaft and provided with a combination of a final drive gear meshing with a final driven gear of a differential device and a reverse idler gear meshing with the reverse drive gear.
Further, the first clutch as well as the second clutch was disposed at a location not overlapping the output shaft in radial directions. By doing so, the automatic transmission could have radially reduced outside dimensions, affording for the automatic transmission to be down-sized with enhanced power transmission efficiency.